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969
AGUS73 KMSR 251819
HMDMSR

HYDROMETEOROLOGICAL FORECAST DISCUSSION
NWS NORTH CENTRAL RIVER FORECAST CENTER TWIN CITIES/CHANHASSEN MN
1225 PM CST TUE NOV 25 2014

...PRECIPITATION...

DURING THE PAST 24-HOURS...A MIXED BAG OF PRECIPITATION IN THE
FORM OF RAIN...SLEET AND SNOW FELL ACROSS EASTERN
MINNESOTA...EASTERN IOWA...WISCONSIN...NORTHERN
ILLINOIS...NORTHERN INDIANA...WISCONSIN AND MICHIGAN AS COLDER
TEMPERATURES MOVED INTO OUR REGION YESTERDAY. LIQUID TOTALS WERE
GENERALLY A THIRD TO ONE INCH ACROSS WISCONSIN...MICHIGAN...
ILLINOIS AND INDIANA.  THE REMAINDER OF THE AREAS REPORTED LESS
THAN A TENTH OF AN INCH.

DURING THE NEXT 24-HOURS...LIGHT SNOW IS FORECAST ACROSS THE
DAKOTAS...MINNESOTA...IOWA AND AROUND THE GREAT LAKES REGION.
SNOWFALL TOTALS OF 2-6 INCHES POSSIBLE.

...HYDROLOGIC CONDITIONS...

MINOR FLOODING IS FORECAST FOR A FEW SITES IN NORTHERN INDIANA AND
LOWER MICHIGAN AS A RESULT OF WEEKEND RAINS AND SNOWMELT.

THIS HAS BEEN A CHALLENGING EVENT TO FORECAST FOR A NUMBER OF
REASONS..

   - PRECIPITATION GAGE QUALITY CONTROL

     QUALITY CONTROL OF TIPPING BUCKET PRECIPITATION GAGES HAS
     BEEN DIFFICULT BECAUSE WARM TEMPERATURES HAVE MELTED SNOW
     THAT ACCUMULATED IN THEM.

     OTHER GAGES HAVE BEEN COVERED
     AND REPORTED ZEROS.  IN EITHER CASE.. THEY DO NOT REPRESENT
     THE AMOUNT OF RAIN THAT FELL.

   - RIVER ICE

     MANY RIVERS WERE ELEVATED COMING INTO THIS WEEKEND DUE TO
     FREEZE-UP ICE JAMS. IT IS DIFFICULT TO DETERMINE THE
     EFFECTS OF THAT ICE ON THE RATING CURVE DURING THE RISE.

     WE HAVE ALSO SEEN SOME RIVER GAGES SPIKE UP AS BREAK-UP
     ICE JAMS FORM AND RELEASE.  WE MUST BE CAREFUL NOT TO ROUTE
     THAT SPIKE DOWNSTREAM BECAUSE IT IS NOT A TRUE
     REPRESENTATION OF THE FLOW HYDROGRAPH.

   - COLD TEMPERATURE FORECAST

     AIR TEMPERATURES ARE FORECAST TO DROP SIGNIFICANTLY DURING
     THE NEXT FEW DAYS.  THE SUB-FREEZING TEMPERATURES MAY FREEZE
     RUNOFF EN ROUTE TO THE RIVERS CAUSING RIVER LEVELS TO DROP
     MORE QUICKLY THAN EXPECTED.

     CONVERSELY.. AT LOCATIONS PRONE TO FREEZE-UP ICE JAMS..
     RIVER LEVELS MAY RISE HIGHER THAN EXPECTED AS THE COLD
     TEMPERATURES AND RELATIVELY HIGH STREAMFLOWS CAN COMBINE TO
     FORM FREEZE-UP ICE JAMS.


FOR ADDITIONAL AND MORE IN-DEPTH INFORMATION CONCERNING RIVER
FORECASTS...PRECIPITATION AND ALL HYDROMETEOROLOGICAL INFORMATION
IN THE NCRFC AREA OF RESPONSIBILITY...PLEASE REFER TO THE NCRFC
WEB PAGE AT:     HTTP://WWW.WEATHER.GOV/NCRFC


EMERGENCY CALL BACK LIST: RJW .. SDB .. BAC .. JCH

IF NO RESPONSE FROM THIS LIST... CALL THE DOH...SCH OR HIC.


$$

...JCH/BAC...






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